Apparatus for detecting organic materials in water

ABSTRACT

A detector device for determining the presence of organic materials in water streams, such as chemical sewers, as a result of leakage or spillage. The device comprises an upright elongated electrically insulating tube through which material from the stream is pumped. At intervals flow through the tube stops, the lighter organic material rising to the top and displacing water downwardly. A pair of spaced apart metal rings near the top of the tube act as plates of an electrical capacitor. As the level of organic material in the tube reaches the location of the rings, the dielectric change changes the electrical value of the capacitor. This change in value is detected and utilized to trigger an alarm. The position of the rings along the tube is adjustable. Using the capacitor as part of the tuned circuit of an oscillator is one means to develop an alarm signal when the oscillator is detuned when the dielectric changes near the rings.

United States Patent [1 1 Parth Nov. 20, 1973 APPARATUS FOR DETECTINGORGANIC MATERIALS IN WATER [75] Inventor: William H. Parth, Saginaw,Mich.

[73] Assignee: The Dow Chemical Company,

. Midland, Mich.

221 Filed: Feb. 4, 1972 21 App1'.No.:223,668

73/231 M, 194 M, 194 E, 61.1 R; 137/392; 324/61 Q5, 61 QL; 331/65Primary Examiner-John W. Caldwell Assistant ExaminerDaniel MyerAtt0mey-Earl D. Ayers et al.

[5 7 ABSTRACT A detector device for determining the presence of organicmaterials in water streams, such as chemical sewers, as a result ofleakage or spillage. The device comprises an upright elongatedelectrically insulating tube through which material from the stream ispumped. At intervals flow through the tube stops, the lighter organicmaterial rising to the top and displac ing water downwardly. A pair ofspaced apart metal rings near the top of the tube act as plates of anelectrical capacitor. As the level of organic material in the 9 tubereaches the location of the rings, the dielectric change changes theelectrical value of the capacitor. This change in value is detected andutilized to trigger an alarm. The position of the rings along the tubeis adjustable. Using the capacitor as part of the tuned circuit of anoscillator is one means to develop an alarm signal when the oscillatoris detuned when the dielectric changes near the rings.

7 Claims, 3 Drawing Figures 56 References Cited UNITED STATES PATENTS2,392,229 1/1946 Cohen 137/392 x 3,397,715 8/1968 Fathauer... 137/392 x3,525,090 8/1970 Raddatz 340/244 (2 Ora/r7 5 !-'4 i l I l I i i 8 i iT/rner i I :,/-56- -J BACKGROUND OF THE INVENTION This invention relatesto organic materials detectors and particularly to apparatus fordetecting spills or leakage of organic materials into chemical sewers orthe like. i

' Leakage or spillage of organic materials into chemical sewers is acommon problem in many chemical production plants. While treatmentfacilities may be sufficient to tolerate small amounts of such leakageor spill- OBJECTS OF THE INVENTION Accordingly, a principal object ofthis invention is to provide an improved reliable detector of organicmaterials in an aqueous stream.

Another object of this invention is to provide an improved, easy toadjust and maintain, detector of organic materials in an aqueous stream.

A further object of this invention is to provide an im-' proved, ruggedand economical to manufacture detector of organic material in an aqueousstream.

STATEMENT OF INVENTION In accordance with this invention, there isprovided an upright elongated hollow column having fluid entry means atleast near to its lower end and discharge means at least near to itsupper end. The upper end part is made of electrically insulatingmaterial. Means are provided for-intermittently pumping an aqueousstream through said column and then holding the stream in a staticcondition for a predetermined interval wherein any organic materialrises to the top of said column. A pair of spaced apart electrodes arecoupled to the exterior of said column along the upper end part near tobut below said discharge means. Each electrode serves as an electrodeelement of a capacitor, each electrode being coupled to means fordeveloping a signal responsive to changes in capacity of said capacitoras organic material displaces aqueous material adjacent to saidelectrodes, and an alarm means actuated by said signal.

BRIEF DESCRIPTION OF THE DRAWING The invention, as well as additionalobjects and advantages thereof, will best be understood when thefollowing detailed description is read in connection with theaccompanying drawing, in which:

FIG. 1 is a diagrammatical view of apparatus in ac- DETAILED DESCRIPTIONOF THE DRAWING Referring to the drawing, there is shown apparatus,indicated generally by the numeral 10, comprising an elongated uprighttube 12 having a lower end 14, a discharge tube 16 coupledto the tube 12near the upper end 18 thereof. The discharge tube 16 may be, forexample, coupled to a drain 20 for return to anaqueous stream (notshown). A line 22 is coupled between the aqueous stream (not shown) andthe input of a pump 24. A line 26 is coupled to the input side of aremotely controlled valve 28 whose output side is coupled to the loweror input end 14 of the tube or column 12 through the line 30.

Another line 32, which extends approximately as high as the top end 18of the tube 12, is coupled to the line 26 between the pump 24 and theremotely controlled valve 28.

The line 32 is open ended and fluid passing therethrough is dischargedusually to a drain.

A ring electrode assembly, indicated generally by the numeral 40, isposition adjustably coupled to the upper part of the tube 12 just belowthe discharge level of the tube. Referring also to FIG. 3, the assembly40 comprises half-collars 60, 62 held together around the tube 12 bymeans of screws or bolts 64.. The ring electrodes 42,44 are retained inspaced apart grooves along the inner peripheral wall of eachhalf-collar. An electrical lead 46 or 48 is coupled from each electrode42 or 44 to a capacitance sensing device such as an oscillator 50 usingring electrodes 42,44 as a part of a tuned circuit and which drawscurrent as a function of the capacitance represented by the ringelectrodes 42,44 and the dielectric material adjacent thereto.

A solenoid switch 52 has its electrical coil coupled to the oscillatorpower supply in series with a circuit whichdraws current as a functionof the capacitance of the ring electrode capacitor. Thus, as the currentchanges due to a change in substance of the liquid at the part of thetube 12 adjacent to the ring electrodes 42,44, the solenoid switch iseither closed or opened.

The timer 38 is coupled indicated by dashed lines 36, 54 to switches 72,respectively. When the switches 52 and 70 are closed electric circuitfrom a source indicated by numeral 58 passes through and actuates thealarm which, for example, may be a light or a bell.

FIG. 2 shows the cycling sequence of the timer 38 which may be a simplemotor driven time having two switching circuits.

In operation, withthe valve 28 opened, a well mixed sample of water andpossible organic contaminants is pumped from a chemial sewer (not shown)through the tube 12 and the bypass line 32. After the tube is wellflushed, the valve 28 closes while the pump 24 continues to operate. Thecontinued operation of the pump 24 maintains a substantially equalpressure on each side of the valve '28 because the height of theby-passline 32 is the same (or as-near as practicable to the same) asthe height of the tube 12 to the discharge part 16.

After the valve 28 closes, organic material lighter than water in thetube in excess of that dissolved in the water rises to the top of thefluid in the tube 12. The ring electrodes 42,44, spaced about onesixteenth inch apart around the tube 12, are positioned a short distancebelow the discharge level of the tube 12. As the water is displaceddownwardly by the rising lighter organic material, the change indielectric constant of the liquid material adjacent to the ringelectrodes 42, 44 changes the capacitance across the ring electrodes 42,44 and results in a change in current through the electrical winding ofthe switch 52. Thus, with the contact of 52 closed, when the timercloses switch 70, the alarm 56 is actuated, giving a visual or audiblesignal, or, alternatively, controlling another system or device.

Some typical organic materials used with the device of FIG. 1 includestyrene, gasoline, benzene and ethyl benzene.

It should be noted that relatively large changes in capacitance occur asthe organic material displaces the water since the dielectric constantof water is approximately 80 while those of the expected organics arebelow 10.

The leads 46,48 are usually the inner and outer leads of a concentriccable.

The oscillator 50 is simply one type of device which may be used withthe ring capacitor assembly 40. A direct reading capacitance device suchas a Foxboro Capacity Dynalog recorder with switch contacts added toclose at pre-set capacitance level has been successfully used.

The volume percent of organics which must be present for an alarm tooccur depends upon the following: 1. The vertical position of thecapacitance detector 50.

2. The geometry of the capacitance detector 50.

3. The length of the tube 12.

4. Increased sensitivity to organics can be obtained by decreasing theinside diameter of the upper portion of tube 12.

The length of the tube or column 12 in one device is fifty inches. Thetube 12 is made of glass. In some instances it may be desirable to makethe lower part of the tube 12 of metal and have only the upper part ofthe tube (near the electrodes) made of electrically insulatingmaterials.

The apparatus of this invention provides a rugged, low maintenance,economical detector for organic materials-in an aqueous stream such as achemical sewer, for example. The tube or column 12 may be disposed in asewer or remote therefrom, with the remainder of the detection apparatuseither remote or close to the tube 12. Adjustment of the sensitivitylevel of the device may be made easily by changing the position of theelectrodes.

What is claimed is:

1. Apparatus for determining the presence of predetermined amounts oforganic materials in an aqueous stream, comprising a generally uprightelongated vertical hollow electrically insulating column, timer actuatedvalved means for controlling the flow of materials from said stream intosaid column, means at least near to the upper end of said column fordischarging liquid from said column, capacitor electrodes, saidcapacitor electrodes being coupled to said column below said meansfordischarging liquid, said capacitor electrodes being electrically coupledto capacitance sensing means for developing an output signal onachievement of a predetermined capacitance between said electrodes, analarm element, said alarm element being actuated in response to saidoutput signal, timer means coupled to said alarm element whereby saidalarm element may be actuated only when said timer actuated valved meansis closed, and means for applying pressurized liquid from said stream tosaid valved means.

2. Apparatus in accordance with claim 1, wherein said capacitorelectrodes are a pair of spaced apart metal rings disposed around theouter periphery of said column.

3. Apparatus in accordance with claim 1, wherein switching means iscoupled to the means for actuating said alarm element, said switchingmeans being actuated by said timer means.

4. Apparatus in accordance with claim 1, wherein said capacitancesensing means is an oscillator which utilizes said capacitor electrodesin a tuned circuit thereof.

5. Apparatus in accordance with claim 1, wherein said means for applyingpressurized liquid to said valve is a pump.

6. Apparatus in accordance with claim 5, wherein bypass flow means areprovided between said pump and said valve, said flow means having adischarge element disposed at least as high as the means for dischargingliquid from said column.

7. Apparatus in accordance with claim 1, wherein the position of saidcapacitor electrodes along said column

1. Apparatus for determining the presence of predetermined amounts oforganic materials in an aqueous stream, comprising a generally uprightelongated vertical hollow electrically insulating column, timer actuatedvalved means for controlling the flow of materials from said stream intosaid column, means at least near to the upper end of said column fordischarging liquid from said column, capacitor electrodes, saidcapacitor electrodes being coupled to said column below said means fordischarging liquid, said capacitor electrodes being electrically coupledto capacitance sensing means for developing an output signal onachievement of a predetermined capacitance between said electrodes, analarm element, said alarm element being actuated in response to saidoutput signal, timer means coupled to said alarm element whereby saidalarm element may be actuated only when said timer actuated valved meansis closed, and means for applying pressurized liquid from said stream tosaid valved means.
 2. Apparatus in accordance with claim 1, wherein saidcapacitor electrodes are a pair of spaced apart metal rings disposedaround the outer periphery of said column.
 3. Apparatus in accordancewith claim 1, wherein switching means is coupled to the means foractuating said alarm element, said switching means being actuated bysaid timer means.
 4. Apparatus in accordance with claim 1, wherein saidcapacitance sensing means is an oscillator which utilizes said capacitorelectrodes in a tuned circuit thereof.
 5. Apparatus in accordance withclaim 1, wherein said means for applying pressurized liquid to saidvalve is a pump.
 6. Apparatus in accordance with claim 5, whereinby-pass flow means are provided between said pump and said valve, saidflow means having a discharge element disposed at least as high as themeans for discharging liquid from said column.
 7. Apparatus inaccordance with claim 1, wherein the position of said capacitorelectrodes along said column is movable.